configs/riotboard: bump u-boot to version 2015.10

Signed-off-by: Nikolay Dimitrov <picmaster@mail.bg>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/riotboard_defconfig

@@ -15,7 +15,7 @@ BR2_ROOTFS_OVERLAY="board/embest/riotboard/rootfs_overlay"
 # bootloader
 BR2_TARGET_UBOOT=y
 BR2_TARGET_UBOOT_CUSTOM_VERSION=y
-BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2015.07"
+BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2015.10"
 BR2_TARGET_UBOOT_BOARDNAME="riotboard"
 BR2_TARGET_UBOOT_FORMAT_IMX=y